Drones are ideal warriors as they can carry out a multitude of military tasks. In Part 1 of the article we had covered the counter measures against drones in the civilian domain. In this article we dwell on measures against drones in the military domain, where they pose a live and potent threat

An Unmanned (Combat) Aerial Vehicle (UAV), also called a drone, in its combat role usually carries at least one of these military systems: surveillance system, electronic warfare system and/or aircraft ordnance such as missiles. Modern technology has enabled more and more capability on smaller and smaller size of unmanned vehicle making them a ferociously potent weapon system.

Anti-UAV/Drone defence system is designed to disrupt and neutralise UAVs engaged in hostile and malicious activity. The Drone is operated by a pilot remotely using line of sight wireless communication or from a communications centre which can be anywhere in the world. The controls then get extended over a satellite link. The Drone may also be programmed with information to fly on its own and complete its designated task.

Uses of a Military Drones

• Reconnaissance, Surveillance, and Intelligence gathering.
• Attack by dropping bombs and/firing missiles.
• Military Communication Relays.
• Electronic Warfare.
• Designation of targets for precision-guided munitions dropped or fired from manned systems.
• Delivery of crucial logistic loads to remote locations.

Types of UAVs/Drones

• Medium-Altitude Long-Endurance (MALE). Fly between 10,000 and 30,000 feet and is designed to orbit over a designated area for 12 to 14 hours e.g. Reaper and MQ-1 Predator; used in the assassination of Iranian military leader Maj Gen Qasem Soleiman.
• High Altitude Long-Endurance (HALE). Fly for a day or two at a time at altitudes exceeding 60,000 feet. Used to perform wide-area surveillance missions using powerful sensors, they are large and expensive e.g. RQ-4 Global Hawk surveillance drone, and the MQ- 4C Triton maritime surveillance variant. On 20 June 2019, Iran shot down a United States RQ-4A Global Hawk drone with a surface-to-air missile over the Strait of Hormuz creating quite a sensation.
• Tactical Drones. Operate at lower altitudes and relatively close to friendly territory (within 100 – 150 Kms) for 8-10 hours e.g. Fulmar X, 3.1 meters in length, weighing 19 kgs, it flies to the altitude of 3,000 meters, achieve a speed of 150 Kms per hour.
• Small Unmanned Aerial System or (SUAV or Minidrone). They weigh less than 50 pounds. Military ground forces make extensive use of microdrones e.g. four-pound RQ-11 Raven for surveillance and artillery spotting and fire control.
• Micro Aerial Vehicles (MAV) or Microdrones. Small handheld short-range spy drone to scout ahead, peering around street corners, behind walls, and over mountain ridges e.g. Black Hornet mini-drone, or Soldier Born Sensor weighing only one ounce with battery life of 20 minutes flight.
• Loitering Munitions or Kamikaze Drones. Generally small, expendable explosive-laden UAVs designed to perform one-way attack missions by crashing into a target e.g. Israel Aeronautic Industry’s Harops (“Harpy”); an Azerbaijani Harops (Harpy) Kamikaze Drone in 2016 crashed into a bus full of Armenian militia, killing seven. Harops have also been used by Israel to knock out Syrian air defence systems.

An Analysis of the Abqaiq–Khurais (Saudi Arabia) Drone Attack: 2019

Uzi Rubin, a prominent Israeli military expert, described the attack as one of the most audacious military surprises ever and a landmark event that bolstered Iran’s prestige domestically and internationally in defiance of the US sanctions.

On 14 Sep 2019, drones were used to attack the Saudi Aramco oil processing facilities at Abqaiq and Khurais. The Houthi movement in Yemen claimed responsibility. The attack caused large fires at the processing facility. Both facilities were shut down for repairs, cutting Saudi Arabia’s oil production by about half – representing about 5% of global oil production. A spokesman for the Saudi-led coalition fighting Iranian-backed rebels in Yemen, stated that 25 drones (perhaps the Samad long-range UAVs of unidentified origin) and missiles were used. Guards at the facilities reportedly tried to bring down the drones with machine gun fire with little success.

What is of concern is that Saudi Arabia’s missile defence system ( at least one MIM – 104 Patriot Missile Defence System at Abqaiq and four other shorter range air defence systems) failed to stop the swarm of drones and cruise missiles that struck the oil infrastructure. Likely reasons:

• The air defence system used was designed to mitigate threats from “high flying targets. UAVs and cruise missiles fly at an altitude too low to be detected by conventional radar systems.
• A swarm of drones and cruise missilescoming from multiple directions can confuse and jam radars, as well as overwhelm air defences.

Russian President Vladimir Putin in a tongue in cheek remark offered to sell Saudi Arabia the advanced S-400 missile system instead of continuing to use the Raytheon Patriot missile system.

The deductions coming out of this attack are serious and require investigation for effective counter measures against Drone attacks.

To Detect and/or Intercept Drones

Detection. Real-time UAV detection is essential for any possible counteraction or elimination.

• Radar. The first detection is usually by an X-band radar (working in the microwave frequency range), providing early warnings. Radars are generally able to find a UAV, but they cannot continuously ‘track’ them, especially at longer distances, or can only do so for a

limited time, intermittently, with interruptions. The probability of detection depends on the target Radar Cross Section (RCS), terrain configuration, and other aspects. The radar must be capable of tracking multiple objects at the same time. Operate in all kinds of weather conditions, and, accurately detect the drone’s position (distance, height, direction). Algorithms are used to distinguish between drones and other small, low-flying objects, such as birds e.g. DeTect HARRIER Drone Surveillance Radar designed for small RCS targets in a complex clutter environment.

• Radio Frequency. Identifies the presence of drones by scanning for frequencies on which most drones are known to operate. The principle is based on evaluation of signals transmitted by the control station (uplink) or by the UAV (downlink), e.g., telemetry data and video signals. Algorithms pick out and geo-locate RF – emitting devices in the area and identify the hostile drones.
• Electro-Optical. These systems detect drones based on their visual signature and identity. Elementary visual detection of the UAV is done by human sight or with optical devices.
• Infrared. These systems detect drones based on their heat signature. The surveillance of the aerial area in the IR domain is mainly used for detection of low altitude aerial targets and is part of an additional surveillance method whereby ‘blind’ areas in the local air picture are covered.
• Acoustic. Detect drones by recognizing the unique sounds produced by their motors. Acoustic systems rely on a library of sounds produced by known drones, which are then matched to sounds detected in the operating environment. Quite like voice recognition in Communication Intelligence. Does not require direct line of sight to the object.
• Combined Sensors. Many systems integrate a variety of different sensor types to provide a more robust and successful detection capability.

Interception. Can be done as follows:-

• Jamming. Is the preferred and safest method for controlling hostile UAVs. Types of Jamming:-

o RF Jamming. Disrupts the radio frequency link between the drone and its operator by generating large RF power output (electromagnetic noise). Once the RF link, which can include WiFi links, is severed, a drone will either descend to the ground or initiate an automatic “return to home” manoeuvre.

o GNSS Jamming. Disrupts the drone’s satellite link, such as GPS or GLONASS, which is used for navigation. Drones that lose their satellite link will hover in place, land, or return to home e.g. Raytheon’s PHASER high-powered microwave system to thwart drone swarms.

• Spoofing. Allows the control of a targeted drone by hijacking the drone’s communications link. (Also known as protocol manipulation, Spoofing refers to taking charge of a drone through hacking of radio signals and transmitting commands to the aircraft from some other control station) This low-power solution offers complete control over the hostile drone and minimal interference with other legitimate signal sources in the area, thus limiting the potential for collateral damage.
• Laser. Destroys vital segments of the drone’s airframe using directed energy, causing it to crash to the ground.
• Nets. Designed to entangle the targeted drone and/or its rotors.
• Projectile. Employs regular or custom-designed ammunition to destroy incoming unmanned aircraft.
• Combined Interdiction. The most used combined interdiction techniques are RF and GNSS jamming systems working in tandem.

Multi-Layered Solutions. Customized multi-layered solutions for finding, tracking, alerting and interdiction of drones are also available. Automatic detection and tracking capabilities include user defined monitoring and alarm zones. Typical Characteristics are:

• Modular and fully configurable 3D radar sensor.
• MIMO radar technologies that help improve detection accuracy.
• Radar tracking bases on MHT (Multi Hypothesis Tracking) algorithm.
• RF sensor that enables including any drone on the socalled white list.
• Acoustic sensor that enables determining the direction from which the drones are approaching.
• Fully integrated and automated directional or omni directional jammer for neutralisation of drones.
• Dedicated web application for controlling the system. Platforms
• Ground-based. Systems designed to be used from either stationary or mobile positions on the ground.
• Hand-held Systems that are designed to be operated by a single individual by hand.
• UAV-based Systems designed to be mounted on drones, which can come into proximity with the targeted unmanned aircraft to employ interdiction elements at close rang

Conclusion

We need to seriously prepare against this live and potent threat. And nations indeed are as is evinced by a latest market study, which has concluded that the global anti drone market is projected to surpass a valuation of USD 3,064 million by the year 2026.The prospects indeed are astronomical.